Question
What happens as the frequency of a signal in coaxial cable is increased?
Answer Options
- A) The characteristic impedance decreases
- B) The loss decreases
- C) The characteristic impedance increases
- D) The loss increases
Correct Answer: D
Explanation
All transmission lines, including coaxial cables, suffer from inherent resistive loss (T7C07) and dielectric loss, which are related to the material’s ability to resist the flow of AC power. This loss is not constant; it depends heavily on frequency.
As the frequency of a signal in coaxial cable is increased, the signal loss increases. This is because the skin effect makes the resistance appear higher, and dielectric losses increase. Therefore, when working on VHF and UHF bands, low-loss (often larger diameter) coaxial cable is mandatory to avoid losing most of your power before it reaches the antenna.
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